"I love working with Nutrisystem. The program is really delivering results for me and I look forward to long term success, staying motivated and helping others do the same," said Hart, who had her third child seven months ago.

Nutisystem said in a statement that it was "thrilled to be helping and working with Melissa" as she becomes the company's new brand ambassador, according to Entertainment Tonight Online.

"She mirrors our values and will resonate with our customers as authentic. Moving forward, you'll see us have an appropriate mix of inspiring celebrities and real life customers who have also enjoyed success. We think dieters are savvier than ever and really appreciate someone who – above all else – is relatable," the statement said.

Hart has three sons with her musician husband Mark Wilkerson, Mason, 7, and Brady, 5, and Tucker, who is seven months old. She is known for her roles in the TV shows "Clarissa Explains It All" and "Sabrina, the Teenage Witch," but currently stars in the ABC Family comedy "Melissa & Joey."

She has also written a memoir, "Melissa Explains It All: Tales from My Abnormally Normal Life," which will hit shelves in October 2013.

The day before Election Day, on Nov. 5, Hart tweeted her support for Mitt Romney and Paul Ryan, sparking criticism among her followers, one of who reportedly told her, “Vote today and punch yourself in the uterus.’’

“I got blasted a lot. I got blasted as I must hate gay people if I’m voting for Romney,’’ Hart told Sean Hannity on Fox News back in November. She added, “I never said I was Republican. I just said who I was voting for . . . I never said anything political.’’Special: These 5 Things Flush 40 lbs. of Fat Out of Your Body.